Current Status of Studies of Mortality for the Hanford and Oak Ridge Plants

Page 1

ENERGY RESEARCH AND DEVELOPMENT ACMlNlSTRATlON CURRENT STATUS OF STUDIES OF MORTALITY FOR THE HANFORD AND OAK RIDGE PLANTS 1. Cause o f Death Analyses a t Hanford before Milham Report. The first analysis of mortality by cause of death was done by Dr. Sanders for the Hanford worker population and siblings in a report dated November 6, 1972. Sanders found no statistically significant findings of Ln te rest in the comparison between workers and siblings in the deaths available through 1969 that were used in the analysis.At that time, analyses relative to radiation exposure inthe employee population had not yet bees carried out. Dr. Milham's paper in preliminary draft was brought to our attention i n May 1974. Dr. Sanders was asked by BER staff to meet with Milham and compare Health and Mortality Study (HMS) data ana results with Milham's. Milham used a zo portion ate mortality ratio (PMR) approach and compared the Hanford population deaths based on death certificates from three counties in the Richland area with Washington State vital statistics. Milham concluded that employment a t Hanford imposed a n excess risk of mortality from cancer of several organ sites,a plastic ii sk to radiation as the causal factor. Milham subsequently revised his data base and analyses in accordance with certain suggestions by Sanders., Tliese changes reduced the number of disease categories for which he considered Hanford employees t o be at increased risk but did not affect those results that indicated excess mortality due t o cancer ofthe pancreas and colon among Hanford workers. Subsequent to his discussions with Milham, Sanders analyzed exposed and unexposed Hanford workers for both total Hanford deaths(rather than only those occurring in the three counties in Washington) anh. confirmed a higher W tion ate mortality ratio for carcinoma of the colon in the exposed workers. This result was not observed i n either the unexposed worker population or the unexposed pooled with

Page 2

/ James Li Liverman between Hanford workers and the state for various cancer sites including those for which the Hanford workers had lower mortality rates than expected were presented by Sanders. higher cancer mortality than expected among Hanford exposed workers for the period l-950-61 but,failing to confirm it for the period 19u - 1972,hec oncluded that a relationship of the cancer incidence data to radiation exposure was notes tai did d, He did find a At that point,the failure of Sanders' analysis to repudiate Milham's findings relative to cancer of the colon and pancreas and the apparent limitation of increased cancer incidence to exposed employees aroused interest e in seeking confirmatory analyses.I suggested to Alex Fremlinn that Battelle's biometric group be requested to investigate in kr ,. end ent ly the Milham * . The Bat tell e analysis, funded by ROO, appeared cent ly in preliminary draft.Since the draft was not reviewed %+%-s a ff adequately before i t was made available to us, i t is being reviewed and revised now aawi11 probably be provided soon inthe form of a preliminary report to supersede the existing draft. As it was carried out,the Bat tell e study was limited to analysis of those deaths that were studied by Dr. Milham, i.e.,deaths occurring in the three counties and methodology. However, those revisions did not alter in an qmportant way Milham's conclusions relative to excess deaths for cancer categories such as colon and pancreas. dld go on to consider radiation exposure data for the same individuals. They found a relatively consistent increase in the percentage of cancer deaths in the highest dose group (above the 90th percentile) when compared with all other dose groups pooled. In addition,a disproportionate percentage of lung cancer cases were foun d in the. high dose group relative to other exposure levels.Qualifications on the validity of the analysis were stated in the draft report ; some of those will be mentioned below. The Battelle group made some corrections in the data The Bat tell e group Future Battelle Analyses. A projection of the additional work t o be done by the Bat tell e biometry group during FY 1976 is attached. extended from that of deaths in the three counties adjacent to and including the plant t o- all Hanford deaths in the HMS files. The analysis will be

Page 3

comparisons will be made between the Kanford population and comparable populations in both Eastern and Western Washington, between exposed and unexposed Hanford workers, and between subgroups partitioned according to cumulative dose, dose distribution in time and internal dose. part of which may be covered by existing funding (up t o $55,000). The time frame for completion of the study is one year., The cost is pro iec ted at $200,000, 6 . Oak Ridge Analyses The Oak Ridge analyses will be conducted by a joint team of ORAU and HNL personnel with Dr. Lushbaugh serving as team leader. Dr. Richmond will forward the protocol for the analyses to be conducted i n Oak Ridge directly to Dr. Liverman. I understand that m gr tal it y rates for cancer types rather proportional mortality rates will be calculated in view of acknowledged deficiencies in The ORAU costs can be covered out of its exis- budp;et i f the r REACTS is restored.If the cut t o$450,003budpp t rPoJlest f o is the near future * It would be unreasonable to expect ORAU t o assume this additional work load while cutting back its program layoffs of personnel will become necessary %e following biases may influence the results of the various analyses conducted t o date: of diseases other than cancer might cause an artificial increase in the proportion of cancer deaths. However, this bias would not affect the comparison of the percentage of cancer cases among all deaths between groups of workers having different radiation exposure levels as carried out by PNL. b. Cancer incidence values for obscure organ sites such as the pancreas may be influenced by the quality of medical diagnosis and the autopsy rate. The superior quality of medical care i n Richland and relatively high autopsy percentage might inflate the mortality rate for Hanford relative to the remainder of the state for the pancreas but would not necessarily do SOfor such organs as the colon and lung, which are diagnosed reliably in

Page 4

c . The differential mobility of persons with cancer as opposed to other disease might affect the mortality rates when based on an analysis of the three Washington counties relative to the of the pancreas may be more likely to remain at the location where the disease is diagnosed. Analyses of the total population of Hanford deaths in the past by Dr. Sanders and in the future by the Bat tell e statisticians will tend t o eliminate this bias. If increased cancer mortality were demonstrable for the high dose group, the relationship of recorded dose to cancer incidence may be distorted by inadequate radiation monitoring during the early periods of plant operation at Hanford and elsewhere,especially prior to the organization of adequate health physics units. This would lead toan understatement af cumulative radiation doses for the affected individuals. An examination of individual work histories extending into the earliest periods of employment for workers in cancer groups of interest may be wa2ranted t o investigate the possible impact cf incomplete cumulative radiation exposure records on dose-response relationships if a response Persons with rapidly progressive disease such as cancer e . Concomitant exposure to agents other than radiation might account for increased disease incidence that would otherwise be attributed 'i'ilese and other potential biases warrant in-depth investigation before atL ri but ion of causal relationships may b e made on the basis of the analyses that have been made o r are in progress. Analysis and Assessment Programs Division of Biomedical and